Calculation method
To estimate the number of calories needed to maintain bodyweight, we have to examine
the three components of daily caloric requirements (1). They are:
- Resting energy expenditure (REE)
- Thermic effect of activity (TEA): which can be further subdivided into two
components:
A. Calories burned during exercise
B. Calories burned after exercise - Thermic Effect of Feeding (TEF)
Total energy expenditure (also called basal metabolic rate) is equal to REE plus TEA plus TEF.
Each component is discussed in detail below.
Resting energy expenditure (REE)
REE represents the number of calories needed by the body to sustain itself at rest. It
typically comprises 60-75% of the total caloric expenditure per day. REE is determined by a
number of factors including total body weight, lean body mass, thyroid hormones, and nervous
system activity (6).
In general, REE correlates closely with total body weight as well as lean body mass. Total
body weight is used to calculate REE due to the difficulty in obtaining accurate measures of lean
body mass (see the previous section on body composition).
There are numerous equations to estimate REE. The simplest method is to multiply total
bodyweight in pounds by 10-11 calories per pound (7). Women should generally use the lower
value, men the higher. Again, this number represents how many calories the body will burn
assuming zero activity.
Sample REE calculation
Female weighing 150 lbs 10 calories/lb = ~1500 calories/day
Male weighing 180 lbs 11 calories/lb = ~1980 calories/day
REE is adjusted upward by determining the number of calories expended during the day,
called the thermic effect of activity.
Thermic Effect of Activity (TEA)
TEA includes general moving around, shivering, and exercise. Depending on the frequency,
intensity and duration, exercise can increase total caloric expenditure by 15% (very sedentary) to
30% or more (very active) over baseline levels. Although it is possible to calculate the number of
calories burned with varying types of exercise, it is generally sufficient to simply estimate the
number of calories burned with activity.
The level of activity in a day will determine the increase in caloric requirements over REE.
(7) Even someone who is totally sedentary will need to adjust REE upwards by at least 15%.
See Table 4 below for REE multipliers: